RU2673503C1 - Method of measuring effort applied to bearing with static and dynamic loading using strain gauges - Google Patents

Abstract

FIELD: measuring equipment.SUBSTANCE: invention relates to methods for measuring axial and radial efforts applied to running rolling bearing and can be used in all components having rolling bearings. When implementing the method, strain gauges are installed on the outer landing surface of the fixed bearing ring. In this case, the strain gauges are installed on sections of the outer landing surface of the stationary ring inclined to the axis of rotation of the bearing. For strain gauges, a calibration is performed for the efforts corresponding to the operating frequencies of rotation, loads and the thermal state of the bearing when working in the assembly.EFFECT: technical result consists in the possibility of simultaneous measurement of both radial and axial efforts applied to the radial-thrust rolling bearing using calibration coefficients.1 cl, 3 dwg

Description

The invention relates to methods for measuring axial and radial forces acting on a running rolling bearing. The invention may find application in all assemblies having rolling bearings.

A known method of measuring axial force by tensometric rings ("Fundamentals of the design of aircraft engines and power plants" authors AA Inozemtsev, MA Nikhamkin, VL Sandratsky. - M .: mechanical engineering, 2008. - T. 1. - 201 s.) Located on both sides of the angular contact rolling bearing. Strain rings are flat elastic rings with thrust pads. Strain gages are installed on flat surfaces between the support protrusions. When an axial force is applied to the support protrusions, deformation of the sites with strain gauges occurs with the appearance of compressive stresses on one side of the site and tensile stresses on the other. Indications for these deformations are graduated on the technological installation. The main disadvantage of this method is the need to use a technological support in the engine, in which strain gauge rings should be installed, which significantly increases the mass of the support and makes it possible to measure only axial force.

Closest to the invention is a method of measuring the radial forces acting on a rolling bearing under static and dynamic loading using resistance strain gauges (copyright certificate No. 212594, publ. 11/29/1968, bull. No. 9, IPC G01M 13/04), in which load cells mounted on a stationary bearing ring. The main disadvantage of this method is the inability to measure axial loads, because This arrangement of load cells allows only radial loads to be measured.

The technical result to which the invention is directed is the possibility of simultaneous measurement of both radial and axial forces acting on an angular contact rolling bearing using calibration factors.

The technical result is achieved by the fact that in the method of measuring the forces acting on a rolling bearing under static and dynamic loading using resistance strain gauges, in which the strain gauges are mounted on the outer seating surface of the stationary bearing ring, in contrast to the known one, the load cells are mounted on bearings inclined to the axis of rotation sections of the outer landing surface of the fixed ring, while the strain gauges perform graduation of efforts corresponding to the working frequency rotation, and thermal loads during operation of the bearing in the node.

The figures show:

FIG. 1 is an example of a strain gauge arrangement.

FIG. 2 is an example of a spectrum of the amplitude-frequency characteristic of dynamic stresses at one of the rotor rotation frequencies.

FIG. 3 is an example of the dependence of dynamic stresses on axial force.

The method is as follows.

On a fixed ring, at an angle to the axis of rotation, grooves are made in which resistance strain gauges are installed. For load cells, a force calibration is performed to determine calibration factors.

To increase the accuracy of calibration, for example, on a technological installation or as part of an engine, the calibration regimes should correspond to the operating frequencies of rotation, loads and thermal state of the bearings during operation in the assembly.

When calibrating according to the results of measurements of dynamic stresses at each moment of time, an amplitude-frequency characteristic is obtained, in which voltage amplitudes at the frequencies of rolling of rolling elements along the raceways of the outer rings are useful signals.

The calibration factor for the force is determined by comparing the amplitude of the stresses at the rolling frequency of the rolling elements and the reference force at the process plant at any given time.

Example.

Using dynamic strain gauging, measurements are made, for example, of axial force in bench conditions on the engine during preliminary tests (Fig. 1). The values of the measured axial loads are determined by the records on the instrumentation of the magnitude of the dynamic stresses measured by strain gauges located on the outer ring of the bearing.

Before testing, the bearing is finalized: in the outer ring of the bearing on the landing surface at an angle to the axis of rotation, grooves are made in which load cells are installed, which are placed in the zone of the highest design stresses, determined on the basis of 3D mathematical modeling of the stress-strain state of the outer ring.

To determine the relationship between the readings of the load cells and the magnitude of the axial force before testing as part of the gas turbine engine, a calibration is performed. Calibration of the load cell readings is carried out on a special technological installation in the range of working frequencies of the rotor of the gas turbine engine and in the range of the expected values of the axial force. Strain gauges are calibrated in two stages: under the action of axial force, both towards the compressor and towards the turbine. To improve the accuracy of calibration, the voltages recorded by all load cells are averaged.

According to the results of calibration, the dependence of dynamic stresses with the frequency of rolling the balls on the axial force (Fig. 2, Fig. 3) is built and then a linear calibration coefficient (K) is determined. For load cells on the compressor side and on the turbine side, their calibration coefficients are determined. During the calibration process, for each individual bearing its own calibration coefficient is determined.

According to the results of measurements of dynamic stresses at each moment of time, an amplitude-frequency characteristic is obtained in which the voltage amplitude at the frequency of rolling the balls along the outer cage is a useful signal. The amplitude of dynamic stresses with a rolling frequency of balls is proportional to the magnitude of the axial load. Based on the obtained amplitude, using the calibration factor, the effective axial force on the bearing at each moment in time and its direction of action are calculated. In this case, the measurement error of the axial force does not exceed 10%.

Thus, this technical solution allows you to perform measurements using calibration factors, both axial force acting on the angular contact rolling bearing, and radial.

Claims (1)

A method of measuring the forces acting on a rolling bearing under static and dynamic loading using resistance strain gauges, in which the strain gauges are mounted on the outer seating surface of the stationary bearing ring, characterized in that the strain gauges are mounted on sections of the outer seating surface of the stationary bearing ring inclined to the axis of rotation of the bearing, at the same time, the strain gauges perform a graduation of the forces corresponding to the operating frequencies of rotation, loads and thermal state the bearing when working in the assembly.

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